It is well established that sharing of syringes between infected and non-infected IV drug users has been a major cause in the spread of AIDS. The development of a single use mechanism that could be incorporated into all disposable syringes would prevent them being salvaged and reused thereby mitigating or eliminating the spread of the epidemic by this path. ANCO proposes to design and develop a special check valve that will close and permanently seal an orifice after the valve has been used once. The valve is small enough to be incorporated either into the syringe body or hypodermic needle without appreciably increasing their present size or shape. This will permit it to be used in both separate and integral needle disposable syringes.